CONSERVATIONAND MATERIALSCOMPATIBILITYIN THE

ARCHAEOLOGICAL SITE OF VIALE TRIESTE 105 (CA) - SARDINIA

Paola Meloni1,2, Gianfranco Carcangiu ,3 Francesco Secchi ,4 Giuseppe Desogus ,5 Roberto Ricciu ,5 Marta

Casti2,5,OmbrettaCocco1,2

1 Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali (DIMCM), Università degli Studi di Cagliari, Via

Marengo2,09123Cagliari,Italy,paola.meloni@dimcm.unica.it,ombretta.cocco@unica.it;

2 Università degli Studi di Cagliari, Laboratorio Colle di Bonaria, Via Ravenna snc, 09125, Cagliari, Italy,

paola.meloni@dimcm.unica.it,marta.casti@unica.it,ombretta.cocco@unica.it;

3 IGAG–CNR - Istituto di Geologia Ambientale e Geoingegneria, UOS di Cagliari, Piazza d’Armi, 09123 Cagliari,

Italy,gcarcan@unica.it;

4 Dipartimento di Scienze della Natura e del Territorio, Università degli Studi di Sassari, Via Piandanna 4, 07100

Sassari,Italy,secchig@uniss.it;

5 Dipartimento di Ingegneria Civile, Ambientale e Architettura (DICAAR), Università degli Studi di Cagliari, Piazza

d’Armi,09123Cagliari,Italy,g.desog@unica.it,ricciu@unica.it,marta.casti@unica.it.

ABSTRACT

Despite the deleterious outcomes resulting from the use of modern materials in the restoration, the problem

of matter’s compatibility is still very much debated. An example is the archaeological area of Viale Trieste

105 in Cagliari (Sardinia), composed by a complex multilayered structures dating from IV-III century BC to

VII century AD. In the 80s, to allow the construction of a parking, a reinforced concrete structure with side

openings was built over the site. The absolute lack of planned preventive maintenance allowed the different

agents of decay to perform their action against the emerging structures, as the contamination of reinforced

concrete’s products of decay (alkaline sulfates). The design of recent restoration has required an accurate

diagnosis and microclimatic monitoring of the site. The XRD revealed that the salts which contaminate

structures are the alkaline sulfates, supporting the hypothesis that their origin can be derived from the

degradation of the cement. The most diffused lithotype is the so-called “pietra cantone”, a biomicritic

limestone whose microstructure favors the phenomenon of salt crystallization. The microclimatic monitoring

has detected intense energy exchanges with the outside as regard the structures closest to the openings,

suggesting greater risk of stresses and permitting the entrance of air pollutants. The results reveal a dramatic

situationfortheconservationofthesearchaeologicalstructures,requiringimminentinterventions.

Key-words:archaeologicalsite,biomicriticlimestone,cement,sodiumsulfatecrystallization, microclimate.